Carbon monoxide stunning of Atlantic salmon (Salmo salar L.) modifies rigor mortis and sensory traits as revealed by NIRS and other instruments

Methods of stunning used in salmon slaughter are still the subject of research. Fish quality can be influenced by pre, ante and post mortem conditions, including handling before slaughter, slaughter methods and storage conditions. Carbon monoxide (CO) is known to improve colour stability in red muscle and to reduce microbial growth and lipid oxidation in live fish exposed to CO. Quality differences in Atlantic salmon, Salmo salar L., stunned by CO or percussion, were evaluated and compared by different techniques (Near Infrared Reflectance Spectroscopy NIRS, electronic nose EN, electronic tongue ET) and sensory analysis.RESULTS: Thawed samples, freeze-dried preparates and NIRS devices proved to be the most efficient combinations for discriminating the treatments applied to salmon, i.e. first the stunning methods adopted, then the back-prediction of the maximum time to reach rigor mortis and finally to correlate some sensory attributes. A trained panel found significant differences between control and CO-stunned salmon: reduced tactile crumbliness, reduced odour and aroma intensities, and reduced tenderness ofCO-treatedfillets.COstunning reduced radiation absorbance inspectra of thawed and freeze-dried fillets, but not fillet samples stored in ethanol, where itmay have interacted withmyoglobin andmyosin. CONCLUSIONS: The good results in a rapid discrimination of thawed samples detected by NIRS suggest suitable applications in the fish industry. CO treatment could mitigate sensory perception, but consumer tests are needed to confirm our findings.